For many years, petroleum has been recovered from subterranean reservoirs through the use of drilled wells and production equipment. Oil and natural gas are found in, and produced from, porous and permeable subterranean formations, or reservoirs. The porosity and permeability of the formation determine its ability to store hydrocarbons, and the facility with which the hydrocarbons can be extracted from the formation. Generally, the life cycle of an oil and/or gas well includes drilling to form a wellbore, casing, cementing, stimulation, and enhanced or improved oil recovery.
Various aspects of the life cycle of an oil and/or gas well are designed to facilitate the extraction of oil and/or gas from the reservoir via the wellbore. A wide variety of fluids is utilized during the life cycle of an oil and/or gas well and are well known. In order to improve extraction of oil and/or gas, additives have been incorporated into various fluids utilized during the life cycle of an oil and/or gas well. The incorporation of additives into fluids utilized during the life cycle of an oil and/or gas well can increase crude oil or formation gas, for example, by reducing capillary pressure and/or minimizing capillary end effects. For example, drilling fluids are utilized to carry cuttings and other particulates from beneath the drill bit to the surface and can function to reduce friction between the drill bit and the sides of the wellbore while maintaining the stability of uncased sections of the borehole. In addition, the drilling fluid and the subsequent cementing and perforating fluids can be formulated to prevent imbibition and/or unwanted influxes of some formation fluids. As another example, fracturing and acidizing are a commonly used techniques to stimulate the production of oil and/or gas from reservoirs, wherein a stimulation fluid is injected into the wellbore and the formation (reservoir). In a typical matrix acidizing or fracturing treatment, from 1 barrel per foot to several million gallons of stimulation fluid are pumped into a reservoir (e.g., via the wellbore). The stimulation fluid can comprise additives to aid in the stimulation process, for example, proppants, scale inhibitors, friction reducers, biocides, gases such as carbon dioxide and nitrogen, acids, slow release acids, corrosion inhibitors, buffers, viscosifiers, clay swelling inhibitors, oxygen scavengers, and surfactants. Later in the life of the well additional fluids and gases may be injected into the well to remediate damage, maintain pressure or contact and recover further oil.
When selecting or using a fluid to be utilized during the life cycle of an oil and/or gas well, it is important for the fluid to comprise the right combination of additives and components to achieve the necessary characteristics of the specific end-use application. A primary goal amongst all aspects of the life cycle of a well is to optimize recovery of oil and/or gas from the reservoir. However, in part because the fluids utilized during the life cycle of an oil and/or gas well are often utilized to perform a number of tasks simultaneously, achieving necessary to optimal characteristics is not always easy.
Accordingly, it would be desirable if a wide variety of additives were available which could be selected to achieve the necessary characteristics and/or could be easily adapted. Furthermore, it is desirable that the additives provide multiple benefits and are useful across multiple portions of the life cycle of the well. For example, a challenge often encountered is fluid recovery following injection of fracturing fluids or other fluids into the wellbore. Often, large quantities of injected fluids are trapped in the formation, for example, in the area surrounding the fracture and within the fracture itself. It is theorized that the trapping of the fluid is due to interfacial tension between water and reservoir rock and/or capillary end effects in and around the vicinity of the face of the fractured rock. The presence of trapped fluids generally has a negative effect on the productivity of the well. While several approaches have been used to overcome this problem, for example, incorporation of co-solvents and/or surfactants (i.e., low surface tension fluids), there is still the need for improved additives, as well as a greater understanding as to how to select the additives to maximize the productivity of the well. The use of microemulsions has also been employed, however, selection of an appropriate microemulsion for a particular application remains challenging, as well as there is a continued need for emulsions with enhanced abilities.
Accordingly, although a number of additives are known in the art, there is a continued need for more effective additives for increasing production of oil and/or gas.